1. Field of the Invention
The present invention relates to certain heat-sensitive recording materials comprised of particular polyphenylmethanes and to thermal papers useful in computer printers or facsimile machines comprised thereof.
This invention especially relates to such heat-sensitive recording materials comprising, e.g., a paper substrate, onto which a colorant precursor and a developer are deposited which, under the influence of heat, coloration is produced from said precursor and developer.
2. Description of the Prior Art
EP-164,417 describes improved heat-sensitive recording materials produced by incorporating with such precursor and developer an optionally substituted benzylbiphenyl or terphenyl which may also be hydrogenated.
Consistent therewith, improved quality is attained, together with a higher printing velocity.
U.S. Pat. No. 4,742,042 describes materials similar to the above, but in which the benzylbiphenyl may be replaced by esters or diesters.
The biphenyls and the terphenyls are expensive to prepare as they require high temperature processes.
According to Ullman's, Encyclopedia of Industrial Chemistry, 5th edition, Vol. A 13, pages 261-265, biphenyl is produced by the hydrodealkylation of toluene at 700.degree. C. and the terphenyls by the dehydrocondensation of benzene at a temperature ranging from 700.degree. to 850.degree. C.